1BSON_STREAMING_BSON(3)              libbson             BSON_STREAMING_BSON(3)
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NAME

6       bson_streaming_bson - Streaming BSON
7
8       bson_reader_t provides a streaming reader which can be initialized with
9       a filedescriptor or memory region. bson_writer_t provides  a  streaming
10       writer  which  can be initialized with a memory region. (Streaming BSON
11       to a file descriptor is not yet supported.)
12

READING FROM A BSON STREAM

14       bson_reader_t provides a convenient API to read sequential  BSON  docu‐
15       ments  from  a file-descriptor or memory buffer. The bson_reader_read()
16       function will read forward in the underlying stream and return a bson_t
17       that can be inspected and iterated upon.
18
19          #include <stdio.h>
20          #include <bson/bson.h>
21
22          int
23          main (int argc, char *argv[])
24          {
25             bson_reader_t *reader;
26             const bson_t *doc;
27             bson_error_t error;
28             bool eof;
29
30             reader = bson_reader_new_from_file ("mycollection.bson", &error);
31
32             if (!reader) {
33                fprintf (stderr, "Failed to open file.\n");
34                return 1;
35             }
36
37             while ((doc = bson_reader_read (reader, &eof))) {
38                char *str = bson_as_canonical_extended_json (doc, NULL);
39                printf ("%s\n", str);
40                bson_free (str);
41             }
42
43             if (!eof) {
44                fprintf (stderr,
45                         "corrupted bson document found at %u\n",
46                         (unsigned) bson_reader_tell (reader));
47             }
48
49             bson_reader_destroy (reader);
50
51             return 0;
52          }
53
54       See    bson_reader_new_from_fd(),    bson_reader_new_from_file(),   and
55       bson_reader_new_from_data() for more information.
56

WRITING A SEQUENCE OF BSON DOCUMENTS

58       bson_writer_t provides a convenient API to write  a  sequence  of  BSON
59       documents  to  a  memory  buffer  that  can  grow  with  realloc(). The
60       bson_writer_begin() and bson_writer_end() functions will manage the un‐
61       derlying buffer while building the sequence of documents.
62
63       This  could  also  be  useful  if you want to write to a network packet
64       while serializing the documents from a higher level language,  (but  do
65       so just after the packets header).
66
67          #include <stdio.h>
68          #include <bson/bson.h>
69          #include <assert.h>
70
71          int
72          main (int argc, char *argv[])
73          {
74             bson_writer_t *writer;
75             bson_t *doc;
76             uint8_t *buf = NULL;
77             size_t buflen = 0;
78             bool r;
79             int i;
80
81             writer = bson_writer_new (&buf, &buflen, 0, bson_realloc_ctx, NULL);
82
83             for (i = 0; i < 10000; i++) {
84                r = bson_writer_begin (writer, &doc);
85                assert (r);
86
87                r = BSON_APPEND_INT32 (doc, "i", i);
88                assert (r);
89
90                bson_writer_end (writer);
91             }
92
93             bson_free (buf);
94
95             return 0;
96          }
97
98       See bson_writer_new() for more information.
99

AUTHOR

101       MongoDB, Inc
102

104       2017-present, MongoDB, Inc
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1091.17.6                           Jun 03, 2021           BSON_STREAMING_BSON(3)
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